SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    84703, 84706, 91053, 88941, 88512, 88141, 
    88144, 88939, 84702, 84705, 91052, 
    84697, 84698, 88946, 88947, 88948, 
    88140, 88143, 88508, 87890, 88943, 
    88944, 88945, 84695, 88937, 87877, 
    88515, 88518, 88514, 88517
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00193

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (84703,84706,91053,88941,88512,88141,88144,88939,84702,84705,91052,84697,84698,88946,88947,88948,88140,88143,88508,87890,88943,88944,88945,84695,88937,87877,88515,88518,88514,88517)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}